by Jacob Resneck, Alexei Korolyov and Anna Arutunyan, USA TODAY

by Jacob Resneck, Alexei Korolyov and Anna Arutunyan, USA TODAY

SEVASTOPOL, Ukraine - Ukraine's interior ministry accused Russia of a "military invasion and occupation" on Friday, saying Russian troops have taken up positions around a coast guard base and two airports on its strategic Crimea Peninsula.

Ukraine's parliament sent an urgent plea to the U.N. Security Council for a meeting on the crisis and adopted a resolution demanding Russia halt actions it says are aimed at splitting Crimea from the rest of the country.

"I can only describe this as a military invasion and occupation," Ukraine's newly named interior minister, Arsen Avakov, wrote in a Facebook post.

The Russia Foreign Ministry confirmed that armored vehicles from its naval base in Crimea were moving around Crimea for "security" reasons, "which is happening in full accordance with the Russian-Ukrainian agreement on the Black Sea Fleet." Russia's defense ministry told the Interfax news agency that there had been "no provocative acts in relation to units and divisions" from Russian forces.

Kiev was not convinced. Ukraine's acting president called on Putin to stop "provocations" in Crimea. The National Bank of Ukraine - the nation's central bank - put a $1,500 limit on foreign currency withdrawals in a bid to counter falling values in the hryvnia, Ukraine's currency.

Oleksandr Turchynov, who was named president after the parliament threw out Ukraine's pro-Moscow president last weekend, threatened that the Ukrainian military "will do its duty" but will not be drawn into provocations.

Confusion erupted Friday over who had taken control of Crimea's two main airports, and who the 50 armed men were who have been occupying the Crimea parliament since Wednesday.

Some officials in Crimea said the men were local defense forces who are pro-Russian; others that they were troops from the Black Sea naval base that Russia leases from Ukraine.

The road to a military airport at Sevastopol was blocked by two military trucks and gunmen wearing camouflage uniforms and carrying assault rifles.

At Sevastopol's Belbek International Airport, around 15 to 20 members of a Ukrainian political party called the Russian Bloc representing ethnic Russians set up an informal blockade to support the armed men with their own civilian barricade a hundred meters from the airport. A private car had coffee, tea and sandwiches in its open trunk, free for anyone to take.

A Russian truck with insignias and number plates removed was spotted exiting the Sevastopol airport.

More checkpoints were set up in the strongly pro-Russian city scrutinizing all arrivals, and Reuters reported that Russian military helicopters traveled to the Crimea.

The blockade may signal an unwillingness to negotiate with Kiev, said Yaroslav Pylynskyi, director of the Kennan Institute at the Wilson Center, a policy research institute in Kiev.

"I heard the people blocking the airport were trying to prevent people from Kiev coming for negotiations," he said. "The (ethnic Russians in Crimea) did not want negotiations, because they are being controlled by Moscow. I guess they also do not know what to do in that situation."

At the airport in Simferopol, commercial flights were landing and taking off despite dozens of armed men in military uniforms without markings who patrolled with assault rifles. They didn't stop or search people leaving or entering the airport, and refused to talk to journalists.

One man who identified himself only as Vladimir said the men were part of the Crimean People's Brigade, which he described as a self-defense unit ensuring that no "radicals and fascists" arrive from other parts of Ukraine.

Political turmoil has been roiling Crimea after the parliament in the Ukraine capital of Kiev threw out the country's pro-Moscow president, Viktor Yanukovych, for allowing the killing of more than 80 protesters.

A defiant Yanukovych, in his first public remarks since he fled Ukraine, declared Friday that he is still the legitimate president of Ukraine but said he would not ask Russia for military intervention to back his claim.

Seated in front of four Ukrainian flags but speaking in Russian, Yanukovych said he was not removed from power but fled Kiev out of fear for his life from "terrorists." He also blamed the "irresponsible" West for backing protesters.

"I am the legitimate president of Ukraine, elected by the people of Ukraine, and was elected in a free and democratic vote," the 63-year-old leader declared.

Speaking to reporters in Rostov-on-Don in southern Russia, he said he has not met with Russian President Vladimir Putin but said Moscow "cannot stay indifferent" to events in Ukraine.

He said Russia should "use all the leverage it has to prevent the chaos, the terror, that is unfolding in Ukraine" but added, "I do not accept any attempts for an intervention to break the sovereignty and integrity of Ukrainian territory."

Austria said it was freezing the bank accounts of Yanukovych, his son, Aleksander, and 16 others linked to Ukraine's former government, the Associated Press reports. Switzerland said it was doing the same.

The United States and Europe have appealed to Russia to stay out of Ukraine affairs; Russia accuses the West of meddling and trying to get Ukraine to weaken ties with Russia.

Moscow has vowed to protect Russian-speaking Ukrainians in Crimea, and has been conducting military exercises near the Crimea border. That raises fears among Ukrainians who recall that the same rationale was given by Russia for intervening militarily into Georgia in 2008.

Sergei Markov, a Kremlin adviser who has worked in Ukraine, said several things needed to happen before Russia decided on an invasion.

"First, there must be strong public support for an invasion among the population," he said. "It has to be massive, like 85%. Putin will not act without that kind of support."

Second, there must either be mass murder of Russians or foreign military intervention."

Fyodor Lukyanov, editor of the Russia in Global Affairs journal and chairman of the Council on Foreign and Defense Policy, says Georgia and Ukraine are different.

"The main difference is the absence in Kiev of a government that has legitimacy," he said. "Ukraine is a large country, while Georgia was more peripheral. There are a lot more risks than in Georgia.

"But there is a demonstration that in case this revolution spreads further into (Eastern Ukraine) regions, then Russia will act."

In recent days, large pro-Moscow rallies in Sevastopol have drawn thousands of jubilant supporters waving the Russian tricolor flag, while the Ukrainian national yellow-and-blue banner is a rare sight in the city.

On Friday, Vladimir Zhirinovsky, one of Russia's most outspoken ultra-nationalist politicians, paid a surprise visit to the city and gave a speech in front of the city's administration building.

"All the roads, all the ports, all the communications are under the control of the provincial Crimean government," he declared to thunderous applause of hundreds of people. "I don't want you to worry whether anything bad will happen tomorrow - let's welcome the Russian flag that is flying over government buildings."

He said the people in Sevastopol could count on Russia's support and said that the land had long been part of Russia - a reference to the fact that Crimea was ceded to Ukraine's Soviet republic in 1954.

"I promise that Russia will render you all kinds of assistance - moral, economic and political," he said.

He then took an opportunity to take a swipe at Ukrainian nationalists who had introduced a bill to downgrade the official status of the Russian language.

"If they want somewhere only to speak Ukrainian, then here we will speak only Russian," he said.